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To accelerate production, LEAP4WA will leverage a state-of-the-art manufacturing platform, named HIP-Vax®, for highly intensified, modular vaccine production through an ongoing partnership with Batavia Biosciences in Leiden, The Netherlands. Batavia is a contract-development and manufacturing organization focused on delivering sustainable, low-cost manufacturing solutions in the field of infectious disease and cancer.

Innovative bioprocess intensification technologies pave the way for significantly higher production efficiency of viral vaccines. Batavia’s HIP-Vax platform combines multiple innovative manufacturing technologies to significantly reduce the cost of producing a vaccine. For example, the production process uses a novel bioreactor design (scale-X™) able to support high cell densities and virus yields per bioreactor volume. As a result, HIP-Vax allows significant miniaturization of the manufacturing facility through which commercial manufacture at lab scale is possible.




Conduct a Phase IIb clinical trial of the Lassa fever vaccine candidate in Liberia, Nigeria, and Sierra Leone.


Strengthen capacity of investigational sites in countries where Lassa fever outbreaks and disease occur frequently.




Facilitate equitable access to the vaccine candidate if it is found to be safe and effective.

Increase the scientific knowledge of how the VSV platform can be applied to address other high-priority emerging pathogens.

LEAP4WA builds on an existing partnership with CEPI that supports a global consortium of partners to conduct Phase I and II clinical trials of the Lassa fever vaccine candidate. The consortium partners are united in their commitment to global equitable access to vaccines, with rVSV∆G-LASV-GPC to be accessible to all populations that need the candidate vaccine, should it be found safe and effective in clinical testing. If positive results are achieved, a stockpile of a new Lassa Fever vaccine could be in place as soon as 2024.

LEAP4WA represents an international collaboration to conduct a Phase IIb clinical trial of IAVI’s Lassa fever vaccine candidate among adults and children in Liberia, Nigeria, and Sierra Leone. The trial aims to enrol 4,950 participants and will run from 2023-2024. Using an innovative recombinant VSV platform and leveraging state-of-the-art manufacturing capabilities, LEAP4WA embodies a comprehensive and collaborative approach to deliver a safe, effective, and accessible Lassa fever vaccine. Collaborators in LEAP4WA represent leading research institutions in Africa, Europe, and North America and together will strengthen capacity of investigational sites in countries where Lassa fever outbreaks and disease occur frequently.


To enable the development of Lassa fever vaccines and strengthen expertise with the VSV vector, an agreement was reached in 2017 with the Public Health Agency of Canada (where the research vaccine was initially tested) which granted IAVI a non-exclusive licence for the development, regulatory approval, and supply of a new vaccine candidate against Lassa fever virus.


The Lassa fever vaccine candidate being studied, rVSV∆G-LASV-GPC, uses a recombinant vesicular stomatitis virus (rVSV) vector — the same rVSV platform used for the rVSV-vectored Ebola Zaire vaccine, ERVEBO®, a highly efficacious vaccine licensed by Merck, which is now registered for use in eight African countries. rVSV∆G-LASV-GPC provided high-level protection from Lassa fever in previously conducted preclinical animal studies.

Vesicular stomatitis virus, or VSV, is made up of five proteins, its viral envelope, and genomic RNA. Already proven against Ebola, this vector shows broad potential for use against pathogens such as Lassa Virus and beyond.

This trial also seeks to inspire additional collaborative and end-to-end vaccine development models needed to advance global public health more broadly, while providing richer knowledge of how the VSV platform can best be applied to address other high-priority emerging pathogens.


In July 2021, IAVI launched a Phase I trial of the rVSV∆G-LASV-GPC vaccine candidate, becoming the third Lassa vaccine to enter the clinic. The Phase I trial is evaluating 110 participants. Following the Phase IIa trial, which will evaluate 400-500 participants, our subsequent Phase IIb study will provide us with crucial proof-of-concept efficacy data from populations located in regions prone to outbreaks of the potentially deadly disease.



THREE-YEAR PLAN: 2022-2024

It is anticipated that it will take at least until 2024 to conduct the preclinical work, develop state-of-the-art technologies to support efficient manufacturing of VSV-based vaccine stockpiles, complete product testing, and conduct the clinical studies needed for product approvals.


The strategic activities of LEAP4WA will enhance the in-country capacity of existing trial sites in endemic countries to conduct clinical trials for vaccines against Lassa fever and other emerging infectious diseases toward controlling future outbreaks. In parallel, the study will strengthen the north-south partnerships among researchers through well-aligned R&D capacity developments. In support of cultivating the next generation of scientific leadership in the region, LEAP4WA also hosts five master students under the mentorship of the consortium’s leadership.



LEAP4WA takes a careful and informed approach to community engagement to ensure that the study avoids any potential for social harm such as discrimination, gender-based violence and stigma to study participants, especially those most vulnerable, including adolescent women and young girls. This approach to community engagement will ensure that the communities who seek to benefit from this research are accessible and, with careful outreach initiatives, will be willing to participate in potentially lifesaving scientific research.

The issue of access is paramount. The consortium partners remain united in their commitment to affordable and equitable access to a Lassa fever vaccine, with rVSV∆G-LASV-GPC to be accessible to all populations that need the candidate vaccine, should it be found safe and effective in clinical testing. This is particularly important for lactating and pregnant women in heavily impacted areas of West Africa, who often bear the heaviest burden of Lassa fever outbreaks and are poorly served by existing treatment options. 

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